Correspondence. 



567 



former would have dropped at Jamrud, the latter gone on to Peshawur, 

 and this is precisely the fact." 



The conclusions of Dr. Lord are exceedingly plausible, and that the 

 tracts of country which he has marked out were originally the basins 

 of lakes, is not at all improbable ; such was originally the case with the 

 valley in which the town of Bilappore on the Sutledge is built, and here 

 you have evidence of the lake having occupied a level some three 

 or four hundred feet above the present bed of the Sutledge. The 

 same we shall prove — and that too from incontrovertible facts, to 

 be applicable to a series of other valleys on the banks of that river ; 

 we shall also prove that the great valley through which the Sicat 

 river flows, whose waters are discharged into the bay at the city of 

 Mundi, was also in the same position, but that the time when these 

 lakes were emptied is geologically speaking comparatively recent, and 

 connected probably with those convulsions and upheavings which raised 

 the Sevalick or sub-Himalayan range to its present position. But we 

 are quite at a loss to make out what he means by unquestionable 

 geological facts, such as the structure of igneous rocks, poured out 

 under strong pressure, &c. 



That igneous rocks are distinguished from volcanic rocks by their 

 structure, by the method of their formation, as he has mentioned, and 

 also in not presenting any crater of eruption, is generally known. But 

 he does not inform us whether those so-called igneous rocks have been 

 the means of causing those convulsions which converted these lakes 

 into valleys ; if so, then they (igneous rocks) must belong to an epoch 

 of comparatively recent date, because he mentions the presence of 

 fossil shells belonging to the genera Planorbis and Paludince, both of 

 which belong to the tertiary series, and many species of which are now 

 in existence. If then he met with these shells imbedded in a rock 

 upraised by the "igneous rocks," thus, — 



a Igneous rooks. 



b Lacustrine deposits, 

 containing Planorbis, &c, 



he is entitled to infer that the eruption of "igneous rocks" took 

 place posterior to the deposition of the fresh water deposits, as the 

 shells mentioned have only been met with in deposits of this descrip- 

 tion. If again, on the other hand, he found the lacustrine formation in 



